The Thunderwing Butterfly is an item from The Legend of Zelda: Breath of the Wild. Link can cook with it and monster parts to create an Electro Elixir which increases Link's resistance to lightning and electricity. They tend to appear in most areas more commonly went it rains including thunderstorms though it is apparently insulated from lightning and static electricity in the atmosphere by an insulating compound produced by organs in its body. Beedle sells them at certain stables.